A Harry Styles solo track has been leaked online.

Fans of One Direction are worried 'Don't Let Me Go' could spell the beginning of the end for the 19-year-old heart throb's time in the band.

The 'Little Things' hitmaker reportedly recorded the early demo with friend Sam McCarthy in 2011 and although the track is said to have been him ''practising'' for his work on the boy band's own music, the source does reveal Harry has been working on his own ''for a long time''.

An insider told the Daily Mirror newspaper: ''Harry loves music and has been enjoying experimenting with his own material for a long time.

''This is just a demo - an early one Harry recorded. He's actually developed much more of a personal style since he made this one.

''He's contributed to the band's albums, and this was basically him practicising for that. He's not going anywhere just yet.''

While a spokesman for the quintet confirmed it was a demo, it still seems there could be more unreleased solo material waiting to be revealed.

The spokesman said: ''It's an old song from a year and a half ago and was a demo for a possible 1D album track.''